Incidence and genetic diversity of Prune dwarf virus in sweet and sour cherry in Bulgaria

Abstract

Sweet cherry is an important fruit crop in Bulgaria. One of the most common viruses of sweet cherry and other stone fruits in the world is Prune dwarf virus (PDV). Field surveys were conducted in 43 commercial and 3 collection sweet and sour cherry orchards at 10 locations in six regions of Bulgaria. Leaf samples from 2090 trees showing and not showing virus-like symptoms were tested by double antibody sandwich-enzyme linked immunosorbent assay (DAS-ELISA) for PDV infection. The average PDV infection level in sweet and sour cherry was 14.4%. In 92.4% of the trees, PDV caused single infection, whereas in 7.6%, it caused mixed infection with Prunus necrotic ringspot virus (PNRSV). Visual observations were made to connect the symptoms with PDV infection. There were PDV symptoms in 56.2% of infected trees whereas, 43.8% of the trees were asymptomatic. The coat protein (CP) sequences of 14 isolates from four regions were determined. The obtained sequences were 654 nucleotides (nts) in length, translated to 218 amino acids. Sequence comparisons showed 87%-100% to 93%-100% identity at nucleotide and amino acid level, respectively. Phylogenetic analyses using nucleotide and amino acid sequences of the CP genes of PDV isolates from Bulgaria and 38 cherry isolates retrieved from the GenBank database indicated the existence of three and two phylogenetic groups, respectively. No association between the phylogenetic grouping of the studied isolates and the symptoms of infected trees and/or the sampling-region was observed.

Variability of some isolates of Prunus necrotic ringspot virus and Prune dwarf virus infecting sour and sweet cherry in Ukraine

“…It should be noted that chlorosis was the most common symptom among all surveyed trees. These symptoms are characteristic of PDV infection and have been repeatedly described by a number of authors (Massart et al, 2008;Smith et al, 1988;Sanchez et al, 2015;Kamenova et al, 2019).…”

“…Both viruses belong to Ilarvirus genus, Bromoviridae family (Pallas et al, 2012). In fruit trees, infection by these viruses leads to a variety of symptoms, the manifestation of which depends on climatic conditions and the type of host plant (Kamenova et al, 2019).…”

“…PDV causes chlorotic rings and spotting, deformation (thinning and curling) of leaf blades, and shortening of internodes (Kamenova et al, 2019). PNRV induce similar symptoms to PDV, and is also manifested by necrotic and chlorotic spots, mosaic and deformation of leaves, flowers and fruits, but often remains latent (Sokhandan-Bashir et al, 2017).…”

“…These pathogens are particularly dangerous for sour and sweet cherry, peach, and almond (Umer et al, 2019). Crop yield is reduced due to the decrease in the number of fruit buds caused by these two viruses (Kamenova et al, 2019). Under the influence of these pathogens, peach yield can be reduced by 60 % (Umer et al, 2019).…”

“…In addition to transmission by grafting and other agronomic measures, spreading by pollen is a typical way of transmission (Çağlayan et al, 2011;Pallas et al, 2012). Due to their ability to transmit by pollen, PDV and PNRSV can spread rapidly in stone crop orchards and cause significant economic damage (Amari et al, 2007;Çağlayan et al, 2011;Kamenova et al, 2019;Nemeth, 1986;Umer et al, 2019).…”